Slide 1
DENGUE RECENT UPDATES FROMDR.MONIKAINTRODUCTION
Dengue fever is the most prevalent arthropod borne disease
caused by flavivirus.4 serotypes of DENV (DENV 1-4) are transmitted
to humans primarily by the bite of Aedes aegypti mosquito.Risk of
disease is higher with areas having multiple endemic serotypes DENV
2 and 3 Severe Disease (Epidemic DHF)
Dengue clinical syndrome
There are actually four dengue clinical syndromes:
Undifferentiated fever;
Classic dengue fever;
Dengue hemorrhagic fever, or DHF; and
Dengue shock syndrome, or DSS.
Dengue shock syndrome is actually a severe form of DHF.
EpidemiologyDengue is the most rapidly spreading mosquito-borne
viral disease in the world. In the last 50 years, incidence has
increased 30-fold with increasing geographic expansion to new
countries and, in the present decade, from urban to rural
settingsAn estimated 50 million dengue infections occur annually
and approximately 2.5 billion people live in dengue endemic
countries.In India first outbreak of dengue was recorded in 1812A
double peak hemorrhagic fever epidemic occurred in India for the
first time in Calcutta between July 1963 & March 1964In New
Delhi, outbreaks of dengue fever reported in 1967,1970,1982,
&1996GEOGRAPHICAL DISTRIBUTION
From- WHO guidelines5GEOGRAPHICAL DISTRIBUTION
Dengue Endemic Areas(1996 to 2010 )
Risk factors:
Construction activities
Water-storage practices
Population movement Heavy rainfall
Vector abundance
Reference - from Clinical Guidelines of dengue National vector
born diseases control programme 2008
8
Seasonal trends of Dengue / DHF 2003-07Reference-from Clinical
Guidelines of dengue National vector born diseases control
programme 20089VECTOR OF DENGUE
Dengue is transmitted by the bite of female Aedes mosquitoFemale
Aedes mosquito deposits eggs singly on damp surfaces just above the
water line. Under optimal conditions the life cycle of aquatic
stage of Ae. Aegypti (the time taken from hatching to adult
emergence) can be as short as seven daysThe eggs can survive one
year without water. At low temperature, however, it may take
several weeks to emerge.During the rainy season, when survival is
longer, the risk of virus transmission is greater. It is a day time
feeder and can fly up to a limited distance of 400 meters. To get
one full blood meal the mosquito has to feed on several persons,
infecting all of them.
Few common and favoured breeding places/sites of Aedes
aegypti
Reference - from Clinical Guidelines of dengue National vector
born diseases control programme 2008
11 TRANSMISSION CYCLE OF DENGUE
1.The virus is inoculated into humans with the mosquito
saliva.
2.The virus localizes and replicates in various target organs,
for example, local lymph nodes and the liver.
3.The virus is then released from these tissues and spreads
through the blood to infect white blood cells and other lymphatic
tissues.
4.The virus is then released from these tissues and circulates
in the blood.
5.The mosquito ingests blood containing the virus.
6.The virus replicates in the mosquito midgut, the ovaries,
nerve tissue and fat body. It then escapes into the body cavity,
and later infects the salivary glands.
7.The virus replicates in the salivary glands and when the
mosquito bites another human, the cycle continues. Patho-physiology
of DHF
Reference - from Clinical Guidelines of dengue National vector
born diseases control programme 2008
13Clinical Features Dengue fever- Incubation Period : 7-10 days
Fever : 5-7 days associated with retro- orbital pain, myalgias,
backpain, polyarthralgias (break bone fever) Rash Centrifugal
distribution Erythematous/Urticarial / Scarlitiniform Palmo Plantar
edema and pruritus
Clinical Features
Clinical Features Dengue Hemorrhagic Fever- WHO classification
of DHF
Thrombocytopenia (platelet count 20% , Hypoproteinemia
,Effusions )
Mortality is 10-20% if untreated, but decreases to 50,000/
cumm.
Aspirin/NSAID like Ibuprofen etc should be avoided since it may
cause gastritis, vomiting, acidosis and platelet
disfunction24INDICATIONS FOR HOSPITALIZATION
TachycardiaCold extremitiesWeak pulseNarrow pulse
pressureHypotensionChanges in mental stateOliguriaIncreasing
haematocrit even after fluid replacementBleeding
Daily Record Of Parameters During HospitalizationNEED FOR IV
FLUIDS
Plasma volume is reduced Volume loss may be upto 20%Evidence of
plasma leakage (Pleural Effusion, Ascites, Increased haematocrit,
Hypoproteinemia)Identify Pre shock Stage; increasing symptoms:
abdominal pain, persistent vomiting, altered mental state
FLUID CHARTS
FLUID CHARTS
SIGNS OF RECOVERY
Stable pulse, blood pressure and breathing rateNormal
temperatureNo evidence of external or internal bleedingReturn of
appetiteNo vomitingGood urinary outputStable
haematocritConvalescent confluent petechiae rash
COMPLICATIONS
Hepatitis - 11%Meningitis Encephalitis DIC Myositis with
RhabdomyolysisIncreased amylase levels and pancreatic enlargement
on USG in 45%ARDSAcute onset; Pa02/FiO2
